Characteristics-Varying Systems in the D-Module

This paper proposed clustering algorithms applied Gaussian basis function neural network compensator with fuzzy control for magnetic bearing system (MBS). The nonlinear MBS improved traditional bearing friction losses, and nonlinear system with fuzzy controller and neural network does not require precise MBS mathematical model. We used clustering algorithms which are fuzzy c-means and k-means adjusted Gaussian basis function in neural network. Finally, we used the Lyapunov stability to guarantee MBS convergence, and the experimental results shows proposed algorithm has satisfactory performance in MBS.

This paper proposes a new nonlinear control system to realize a zero power control of magnetic bearing system using only electromagnets. The nonlinear control system is designed based on Lyapunov's direct method. The electromagnets is switched by the nonlinear algorithm depend on the displacement and the velocity of a rotor. It is very easy to design the nonlinear control system because it consists of only two parameters. Also, the characteristics of closed loop can be changed easily. Stability of magnetic bearing system controlled by the proposed nonlinear control is proved. It is clarified through the simulation that the proposed nonlinear control in this paper is a very useful approach to realize a zero power control of magnetic bearing system.

Adaptive backstepping control for magnetic bearing system via feedforward networks with random hidden nodes

As an introduction to this report I would like to cite two comments from the book MK Process and Stellar Classification (ed. by R.F. Garrison, 1984). The first is from the article by W.W. Morgan The MK system and the MK process: “The MK system furnishes a satisfactory frame of reference for stars of Population I in the solar neighborhood; but when we consider the variety of stellar spectra encountered in our galaxy and in other stellar systems we are unable to classify many stars satisfactorily from the MK standards alone. What we now require is a more general frame of reference – or frames of reference – that will accept with precision a greater variety of ‘specimens’ (stellar spectra).” The second is an excerpt from one of the conclusions in the article by D.L. Crawford The relationship between the MK system and photometric classification: “The future potential of all this classification work is great. Technological change is rampant, and most interesting. New and powerful 1(λ) machines will be with us soon, as well as direct CCD photometers. Their power is great and we’ll all end up using them. The opening of new wavelength regions is a fantastic advantage to classifiers. The challenges and opportunities are vast.”During the last three years there have been technical improvements in CCD detectors and as a result they are now much better adapted to the needs of photometry and spectroscopy. Signal processing by modern computers now permits rapid utilization of large quantities of information. Technical progress in detectors and computer science now provides us with powerful and relatively low-cost tools for computation, and leads us to view with optimism the development of the powerful 1(A) machines anticipated by Crawford.

In this paper, a novel robust nonlinear control scheme is proposed for a basic current-controlled active magnetic bearing (AMB) that is non-affine in the control input. First, a dynamic model approximation technique is developed to facilitate the controller design. Then, since the control characteristics of the AMB are highly nonlinear and time-varying with external disturbance, the robust nonlinear control system with an extended state observer is proposed to improve the control performance and increase the robustness of the AMB control system. Finally, The proposed approach is applied to a flywheel which is supported by four current-controlled active magnetic bearings. Simulation results are included to show the effect of the proposed new control design techniques.

In this study, we focus on the error of estimated frequency of disturbance and present a new adaptive frequency tracking and new modification law after examining relation between the error of frequency and output level in detail. We also develop a multiple frequency estimation algorithm, which is insensitive to observation noise and prove the asymptotic stability for adaptive nonlinear algorithm and adaptive frequency tracking method theoretically. The results of simulation show that when estimated frequency by difference equation method approach to the true value, then the output error converges to zero (or equilibrium point) asymptotically. This corresponds to the asymptotic stability condition. The effectiveness of this method and the theoretical proof are verified by simulation. The experimental results show that the proposed algorithm is effective for achieving unbalance vibration suppression.

Brushless doubly fed induction machine has recently attracted attention in variable speed generators and motor drives. In order to have a high performance control, a precise dynamic model is required. This paper aims at introducing a model of brushless doubly fed induction machine taking core loss into account. The details of model derivation are outlined and the torque relation is expressed in the general reference frame. The model is then used for simulation of the dynamic performance of the machine. The error introduced by neglecting core loss effect is also shown.

Magnetic-bearings, which support shafts with magnetic levitation rather than mechanical contact, have been in industrial use for decades. Recent technological developments, especially in digital processing and control, have made magnetic bearings a more-robust and cost-effective design solution than ever. The dynamic characteristic of electromagnetic bearing depends upon adopted controller; the active control can makes the electromagnetic bearings to realize complex control and special control. With the development of signal processing technology and modern control theory, the main parts of the control system are the digital signal-processing (DSP) electronics, a power supply, and amplifiers. An Active Magnetic Bearing (AMB) controller is mainly discussed in the paper, which is to be solved to realize this flexible control by hardware design based on DSP using TMS320C32 processor. It is proved by experiment that this kind of controller can optimize for this system, improve its stability and also have a very important referential value on the further study of AMB system.

Based on TMS320C6713 DSP of TI and XC95288XL CPLD of Xilinx, the hardware circuit of the controller is designed for the five-degree-freedom active magnetic bearing(AMB) flexible rotor system. Under the CCS3.3 development environment, the design uses C language to program a position PID control algorithm. The results of experiment show that magnetic bearing control system has strong robustness and anti-jamming capability using this controller. Keywords-active magnetic bearing; TMS320C6713 DSP; CPLD; position PID

Magnetic bearings can not only solve the bearing wear and life problems but also reduce the loss and noise of bearings. However, the strong non-linear and uncertainty of parameter of the magnetic bearings make the traditional PID controller difficult to ensure its long-term and stable operation. Based on the theory of quantitative feedback theory (QFT) and H∞ control theory, this paper presents a design method of magnetic bearing controller for high speed motors. QFT is able to implement design requirements to robust stability and robust performance of the system with large scope uncertainties, but it requires loop-shaping on the Nichols chart and tedious graphical process. Based on QFT, the adoption of H∞ control theory can reduce the drawing process which greatly simplifies the design process. The simulation and experimental results show that the proposed QFT-H∞ controller makes the control system of magnetic bearings have a strong anti-jamming performance for uncertainty of parameters and loading disturbances to ensure the long-term stable operation of the magnetic bearings.

Institutional theory is an important framework for various research fields. It gives a general frame of reference as to what constitutes an institution and what are the factors that affect it. However, the theory requires more than a general frame of reference because in today’s world the characteristics of the organizations are changing with the change in factors related as well as unrelated to the processes of organization. In this background, the paper attempts to provide a brief historical overview of institutions, institutionalisation, differences among institutions and institutional environment to unveil the development of institutional theory. It also looks at the application of institutional theory in the context of multinational enterprises. The findings indicate that emphasis of institutional theory has shifted from generalized system of social belief to appropriate means to become legitimate with the pressures.

Form of the quantum kinetic energy operator for relative motion of a group of particles in a general non-inertial reference frame

This paper offers new insights into gravitational interactions within a general non-inertial reference frame. By utilizing symbolic tensor calculus, the study establishes a unified framework that connects time derivatives in non-inertial frames to those in inertial frames. The research introduces new first integrals of motion for a system of many particles in arbitrary non-inertial and barycentric rotating reference frames. These first integrals provide a kinematic and geometric visualization of motion in non-inertial frames. Additionally, a generalized potential energy function is presented for broader applicability. For the gravitational two-body problem, the paper delivers a closed-form, coordinate-free solution for the motion of each body relative to the original frame. Consequently, sufficient conditions for stability against collisions are established within the context of the two-body problem in a non-inertial reference frame. Furthermore, the paper examines the relative orbital motion of spacecraft, presenting a closed-form and coordinate-free solution in the local vertical local horizontal (LVLH) non-inertial frame, which is centered on the center of mass of the main spacecraft.

The state equation of five degrees of freedom rotor system suspended by AC hybrid magnetic bearings is given, and the approach to how to use linear quadratic method of optimal control theory to design a centralized and decentralized parameter controller is introduced. The simulation analysis between the centralized and decentralized parameter controllers is completed using MATLAB software. The digital control system based on TMS320F2812 DSP for AC magnetic bearings has been designed and tested using the decentralized control arithmetics. The research results have shown that the decentralized controller based on linear quadratic method meets performance requirements of AC magnetic bearing system, and has good control effect when the speed of the rotor runs under 30000 rpm.

Mathematical models are disappointing due to uneven distribution of the air gap magnetic field and significant unmodeled dynamics in magnetic bearing systems. The effectiveness of control deteriorates based on an inaccurate mathematical model, creating slow response speed and high jitter. To solve these problems, a model-free adaptive control (MFAC) scheme is proposed for a three-degree-of-freedom hybrid magnetic bearing (3-DoF HMB) control system. The scheme for 3-DoF HMB depends only on the control current and the objective balanced position, and it does not involve any model information. The design process of a parameter estimation algorithm is model-free, based directly on pseudo-partial-derivative (PPD) derived online from the input and output data information. The rotor start-of-suspension position of the HMB is regulated by auxiliary bearings with different inner diameters, and two kinds of operation situations (linear and nonlinear areas) are present to analyze the validity of MFAC in detail. Both simulations and experiments demonstrate that the proposed MFAC scheme handles the 3-DoF HMB control system with start-of-suspension response speed, smaller steady state error, and higher stability.